In the UK it is the greed of the money lenders un-regulated (or unenforced) by the government.
It used to be that you had to have a substantial deposit and you could then borrow twice annual income. Of course, this meant your choice of properties was pretty limited.
So then they start to lend more, and to help out those first few years, special interest rate deals so you could afford to pay a higher mortgage while your income wouldn't support the true value.
SO there is the first assumption:
that as time goes by income will increase to help pay the mortgage.
But, as income increases, so too do expectations. Of course, when you have sat in a house for a while, the price goes up due to supply and demand. SO you ow have equity to boost the deposity value for the next.
Increasing property value is the next assumption In fact, on occassions, it can go down.
That property values haven't gone down so foten as one would expect is because the money lenders have more money to lend.
Now you can borrow more than twice income and you need a smaller deposit.
Of course, this doesn't mean you can afford a better house, it just means that there is more money comp-eting for the same house and the effect of lending more moeny is to increase the selling prices, not to increase the borrowers range of options.
Then we come to self certification. The day they put "financial advisers" into estate agents was a bad one.
Theoretically, you had to prove your income. However, some self employed people could self-certify. This meant that some people would see a property they wanted, work out what they needed to borrow, work out the income they needed to show to get that money and that is the amount they'd certify. It would appear (and I have been told this myself by an "advisor") that they do not check too closely.
Why? because the lenders money is safe.
Why is the lenders money safe? because they lend only part of the property value. So if the borrower defaults on day one they can get their money back and all that is at risk is the borrowers equity or deposit. (Sadly, sales of repossessions are managed by the lender which means that so long as they get their money back they could care less about the borrowers deposit).
Now we come to the next problem.
Because house prices have been rising and rising significantly, the borrowers need more money and the lenders need to lend more.
Every one is pursuaded that house prices can only rise.
Enter the 100% mortgage. Lenders are so convinced that prices can only rise they forget that they are the ones responsible for the phenomenal house price rises so they are convinced that even if the borrower defaults at once the months that have elapsed since the sale was agreed and the default the price will have risen by a few thousand (especially as part of the borrowed amount probably includes improvements).
Now comes the crunch and the whole house of cards start to tumble.
But, where will it end up?
What is the true price of a house?
The victims are not all speculators. Yes, there have been some who decided that because property prices were so rapidly increasing they would borrow every penny they could, modernise the property and then sell it on for a fast profit.
Now enter TV. Once it was cookery shows, then it was holiday shows then gardening. Now it is property development. Countless shows looking at buying and selling, buy to let, in short, how to be a "property" tycoon with no other skill or resource than aspirations and access to easy money.
In the UK many many simple people have been caught out because of the combined greed of the property speculators and money lenders but mostly a lack of regulation by government which for years abdicated its responsibilities.
JMW